How are contact lenses made? Mine always look like perfectly round little dishes of s

dhoom007 · #1 (**permalink**) 08-11-2009, 10:20 PM

How are contact lenses made? Mine always look like perfectly round little dishes of soft plastic.?

anu · #2 (**permalink**) 08-26-2009, 03:08 AM

Quote:

Originally Posted by dhoom007

How are contact lenses made? Mine always look like perfectly round little dishes of soft plastic.?

information about contact lenses..
Contact lenses are small visual devices made with curved pieces of plastic shaped in a way to conform directly to the wearer’s eye. They provide an artificial refracting surface to the human eye and are used to correct vision problems like myopia and hypermetropia. Contact lenses aid in eye focusing in the same manner as spectacles do. Apart from these corrective measures, contact lenses can also be used for cosmetic and therapeutic reasons.

Hogwartz · #3 (**permalink**) 08-26-2009, 10:51 AM

Quote:

Originally Posted by anu

information about contact lenses..
Contact lenses are small visual devices made with curved pieces of plastic shaped in a way to conform directly to the wearer’s eye. They provide an artificial refracting surface to the human eye and are used to correct vision problems like myopia and hypermetropia. Contact lenses aid in eye focusing in the same manner as spectacles do. Apart from these corrective measures, contact lenses can also be used for cosmetic and therapeutic reasons.

That's a nice definition of contact lenses, anu, but the question was about how they're made. This is what the eHow website says:

"1. When making soft contact lenses, manufacturers start with a polymer that has been cut into buttons. Guided by a computer, a digital lathe shapes the inside of the contact based on the lens prescription. The inside of the lens is then polished with an abrasive paste to remove any imperfections that could interfere with vision or comfort. Lens thickness is measured and, if correct, the lens is coated in wax so that the outside of the lens can be molded to the desired shape. Once the outside of the lens has been shaped, ultrasound is used to remove the wax and the outer surface and rims of the lens are polished. The lens is then left in a saline solution for 24 hours so that it can absorb enough liquid to become soft and flexible. The lens is then checked to verify that it matches the prescription and correctly refracts light. After a final cleaning, the lenses are sealed in bottles of a salt solution. These containers are then sterilized and can remain so for up to 7 years.
2. Lenses can also be made by a process known as spin casting. A mold is made and filled with liquid monomer. Monomers are tiny molecules that can be combined in different ways to make polymers--a series of molecules that take on different characteristics depending on how they are put together. The mold is then rotated which creates a lens by polymerizing the monomer. Lens qualities are changed by changing the speed at which the mold rotates or the shape of the mold. Lenses then go through a finishing process of polishing, inspection, sterilization and packaging.
3. Lenses can also be made using an injection molding process. This process involves a mold made up of two halves. The mold pieces are put together and the lens polymer is injected into the mold under pressure. After injection the mold is removed from the lens and cooled. As in the other methods, lenses are then polished, checked for quality control, sterilized and packaged."

Source: http://www.ehow.com/how-does_4569992_how-contact-lenses-made.html

Tonythetiger · #4 (**permalink**) 06-11-2010, 10:24 AM

Quote:

Originally Posted by anu

information about contact lenses..
Contact lenses are small visual devices made with curved pieces of plastic shaped in a way to conform directly to the wearer’s eye. They provide an artificial refracting surface to the human eye and are used to correct vision problems like myopia and hypermetropia. Contact lenses aid in eye focusing in the same manner as spectacles do. Apart from these corrective measures, contact lenses can also be used for cosmetic and therapeutic reasons.

That's what they are, not how they're made.

Now, can you tell me what hypermetropia is?

Tonythetiger · #5 (**permalink**) 06-11-2010, 10:30 AM

Quote:

Originally Posted by Hogwartz

That's a nice definition of contact lenses, anu, but the question was about how they're made. This is what the eHow website says:

"1. When making soft contact lenses, manufacturers start with a polymer that has been cut into buttons. Guided by a computer, a digital lathe shapes the inside of the contact based on the lens prescription. The inside of the lens is then polished with an abrasive paste to remove any imperfections that could interfere with vision or comfort. Lens thickness is measured and, if correct, the lens is coated in wax so that the outside of the lens can be molded to the desired shape. Once the outside of the lens has been shaped, ultrasound is used to remove the wax and the outer surface and rims of the lens are polished. The lens is then left in a saline solution for 24 hours so that it can absorb enough liquid to become soft and flexible. The lens is then checked to verify that it matches the prescription and correctly refracts light. After a final cleaning, the lenses are sealed in bottles of a salt solution. These containers are then sterilized and can remain so for up to 7 years.
2. Lenses can also be made by a process known as spin casting. A mold is made and filled with liquid monomer. Monomers are tiny molecules that can be combined in different ways to make polymers--a series of molecules that take on different characteristics depending on how they are put together. The mold is then rotated which creates a lens by polymerizing the monomer. Lens qualities are changed by changing the speed at which the mold rotates or the shape of the mold. Lenses then go through a finishing process of polishing, inspection, sterilization and packaging.
3. Lenses can also be made using an injection molding process. This process involves a mold made up of two halves. The mold pieces are put together and the lens polymer is injected into the mold under pressure. After injection the mold is removed from the lens and cooled. As in the other methods, lenses are then polished, checked for quality control, sterilized and packaged."

Source: http://www.ehow.com/how-does_4569992_how-contact-lenses-made.html

Nice posting, Hogwartz. You cited the source of the information you posted, and it contained the phrase "polymerizing the monomer."
It's nice to know how contacts are made.

Hogwartz · #6 (**permalink**) 07-20-2010, 12:11 PM

Quote:

Originally Posted by Tonythetiger

Now, can you tell me what hypermetropia is?

It sounds like the home of a futuristic Clark Kent, but really it's just the medical term for farsightedness. If you are nearsighted, you have myopia. If you are farsighted, you are said to have hypermetropia, also known as hyperopia.

I can hear some of you say "I though that was called presbyopia"? Here's what Wikipedia has to say: "Hyperopia is often confused with presbyopia, another condition that frequently causes blurry near vision. Presbyopes who report good far vision typically experience blurry near vision because of a reduced accommodative amplitude brought about by natural aging changes with the crystalline lens. It is also sometimes referred to as farsightedness, since in otherwise normally-sighted persons it makes it more difficult to focus on near objects than on far objects.
The causes of hyperopia are typically genetic and involve an eye that is too short or a cornea that is too flat, so that images focus at a point behind the retina. People with hyperopia can usually see distant objects well, but have trouble focusing on nearby objects."

So hyperopia is brought on by age, and hypermetropia is usually genetic.

sweet gal · #7 (**permalink**) 12-08-2010, 08:58 PM

Contact lenses may be produced by a molding process, through the so-called lathe and the finishing step. The molding method is where the three different fluids are poured into rotating molds. Contact lenses may also be done by cutting on a lathe through the use of a lapping machine and the finishing step is where the peripheral anterior and posterior curves are made. What type of contact lens do you use, the soft or the hard type?

John316 · #8 (**permalink**) 12-09-2010, 11:31 AM

Quote:

Originally Posted by Tonythetiger

Nice posting, Hogwartz. You cited the source of the information you posted, and it contained the phrase "polymerizing the monomer."
It's nice to know how contacts are made.

Always remember to polymerize your monomers. You wouldn't want to be seen with un-polymerized monomers, would you?

Tonythetiger · #9 (**permalink**) 12-15-2010, 05:08 PM

Quote:

Originally Posted by John316

Always remember to polymerize your monomers. You wouldn't want to be seen with un-polymerized monomers, would you?

Certainly not. I'll be careful, John.

John316 · #10 (**permalink**) 01-11-2011, 10:53 AM

Quote:

Originally Posted by Tonythetiger

Certainly not. I'll be careful, John.

That's all I ask, Tony.

Hogwartz · #11 (**permalink**) 01-11-2011, 12:46 PM

Quote:

Originally Posted by Tonythetiger

Nice posting, Hogwartz. You cited the source of the information you posted, and it contained the phrase "polymerizing the monomer."
It's nice to know how contacts are made.

I'm glad you like it, Tonythetiger. In case you were wondering, "polymerization is the process of combining many small molecules known as monomers into a covalently bonded chain." So to "polymerize the monomer" is like making a train out of freight cars.

Tonythetiger · #12 (**permalink**) 01-25-2011, 11:51 AM

Quote:

Originally Posted by Hogwartz

I'm glad you like it, Tonythetiger. In case you were wondering, "polymerization is the process of combining many small molecules known as monomers into a covalently bonded chain." So to "polymerize the monomer" is like making a train out of freight cars.

Here comes a triple-header consist of Santa Fe yellow bonnets.

I'm a train geek, okay?

jamlin · #13 (**permalink**) 02-23-2011, 10:22 PM

Thanks for letting me know

Kyleden · #14 (**permalink**) 02-24-2011, 10:59 AM

Quote:

Originally Posted by Hogwartz

I'm glad you like it, Tonythetiger. In case you were wondering, "polymerization is the process of combining many small molecules known as monomers into a covalently bonded chain." So to "polymerize the monomer" is like making a train out of freight cars.

Thanks for finding an excuse to post a picture of a train on Lens 101. "Santa Fe, All the Way."

Hogwartz · #15 (**permalink**) 02-24-2011, 12:55 PM

Quote:

Originally Posted by sweet gal

Contact lenses may be produced by a molding process, through the so-called lathe and the finishing step. The molding method is where the three different fluids are poured into rotating molds. Contact lenses may also be done by cutting on a lathe through the use of a lapping machine and the finishing step is where the peripheral anterior and posterior curves are made. What type of contact lens do you use, the soft or the hard type?

What are "peripheral anterior and posterior curves?" "Posterior curves" sounds like something you might talk about to sell jeans.

I'd post a picture to illustrate my point, but I don't want to see the word "perv" in this thread directed at me.

Kyleden · #16 (**permalink**) 02-25-2011, 11:45 AM

Quote:

Originally Posted by Hogwartz

What are "peripheral anterior and posterior curves?" "Posterior curves" sounds like something you might talk about to sell jeans.

I'd post a picture to illustrate my point, but I don't want to see the word "perv" in this thread directed at me.

Well, "peripheral" means "around the edges" as in "peripheral vision." "Anterior" means front and "posterior" means back. So to translate, "the finishing step is where the peripheral anterior and posterior curves are made" refers to the curve at the edges of the contact lens, on both the front and the back surfaces.

John316 · #17 (**permalink**) 02-28-2011, 02:57 PM

Quote:

Originally Posted by Kyleden

Well, "peripheral" means "around the edges" as in "peripheral vision." "Anterior" means front and "posterior" means back. So to translate, "the finishing step is where the peripheral anterior and posterior curves are made" refers to the curve at the edges of the contact lens, on both the front and the back surfaces.

Thank you for breaking it down for us Kyleden.

Autonation · #18 (**permalink**) 03-07-2011, 05:01 PM

Quote:

Originally Posted by Hogwartz

What are "peripheral anterior and posterior curves?" "Posterior curves" sounds like something you might talk about to sell jeans.

I'd post a picture to illustrate my point, but I don't want to see the word "perv" in this thread directed at me.

Posterior curves, right, I got it.

So does Eva Mendes.

Contact Lens Fitter · #19 (**permalink**) 03-07-2011, 06:47 PM

Quote:

Originally Posted by sweet gal

Contact lenses may be produced by a molding process, through the so-called lathe and the finishing step. The molding method is where the three different fluids are poured into rotating molds. Contact lenses may also be done by cutting on a lathe through the use of a lapping machine and the finishing step is where the peripheral anterior and posterior curves are made. What type of contact lens do you use, the soft or the hard type?

If I may add, there are two different molding processes. The one mentioned above is 'spin cast' molding. More common these days is 'hydroform' and/or mating surface molding.

dontblink · #20 (**permalink**) 03-08-2011, 11:06 AM

Quote:

Originally Posted by Contact Lens Fitter

If I may add, there are two different molding processes. The one mentioned above is 'spin cast' molding. More common these days is 'hydroform' and/or mating surface molding.

Without getting too technical, how is hydroform and/or mating surface molding different from spin casting?

Hogwartz · #21 (**permalink**) 03-31-2011, 12:03 PM

Quote:

Originally Posted by Contact Lens Fitter

If I may add, there are two different molding processes. The one mentioned above is 'spin cast' molding. More common these days is 'hydroform' and/or mating surface molding.

Nice work not getting distracted by the Mendez picture. I know I just sat and stared with my mouth open for a few seconds.